Bobik T A, Wolfe R S
Department of Microbiology, University of Illinois, Urbana 61801.
Proc Natl Acad Sci U S A. 1988 Jan;85(1):60-3. doi: 10.1073/pnas.85.1.60.
The heterodisulfide of the two coenzymes 2-mercaptoethanesulfonic acid (coenzyme M, HS-CoM) and N-(7-mercaptoheptanoyl)threonine O3-phosphate (HS-HTP) increased the rate of CO2 reduction to methane by cell extracts 42-fold. The stimulation resulted from activation of the initial step of methanogenesis, the production of formylmethanofuran from methanofuran and CO2. These results establish a role for this heterodisulfide (CoM-S-S-HTP) in the reduction of CO2 to formylmethanofuran. Evidence indicates that CoM-S-S-HTP is the labile intermediate that accounts for the coupling of the reduction of 2-(methylthio)ethanesulfonic acid by the methylreductase to formylmethanofuran biosynthesis, the "RPG effect." The heterodisulfide was found to be labile in cell extracts due to enzyme-catalyzed reduction and possibly thioldisulfide exchange.
两种辅酶——2-巯基乙烷磺酸（辅酶M，HS-CoM）和N-（7-巯基庚酰基）苏氨酸O3-磷酸（HS-HTP）的异二硫键，使细胞提取物将二氧化碳还原为甲烷的速率提高了42倍。这种刺激源于产甲烷作用第一步的激活，即从呋喃甲醇和二氧化碳生成甲酰呋喃甲醇。这些结果确立了这种异二硫键（CoM-S-S-HTP）在将二氧化碳还原为甲酰呋喃甲醇过程中的作用。有证据表明，CoM-S-S-HTP是不稳定中间体，它解释了甲基还原酶将2-（甲硫基）乙烷磺酸还原与甲酰呋喃甲醇生物合成的偶联，即“RPG效应”。由于酶催化还原以及可能的硫醇-二硫键交换，发现这种异二硫键在细胞提取物中不稳定。
